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    <ul class="crumbs"><li><a href="../index.html">Home</a></li><li><a href="index.html">inter</a></li><li><a href="index.html#M">Manual</a></li><li><b>Inform Organisation</b></li></ul></div>
<p class="purpose">The standard hierarchy of inter code generated by Inform.</p>

<ul class="toc"><li><a href="M-io.html#SP1">&#167;1. Status</a></li><li><a href="M-io.html#SP2">&#167;2. Global area and main</a></li><li><a href="M-io.html#SP3">&#167;3. Compilation modules</a></li><li><a href="M-io.html#SP8">&#167;8. Function packages</a></li><li><a href="M-io.html#SP9">&#167;9. Looking at the Inter produced</a></li></ul><hr class="tocbar">

<p class="commentary firstcommentary"><a id="SP1" class="paragraph-anchor"></a><b>&#167;1. Status.</b>The line between what is part of the Inter specification, and what is simply
a convention about its use, is a fine one. For example, Inter allows
arbitrary sets of primitives and of annotations, but in practice the Inform
toolchain standardises both: see <a href="M-ip.html" class="internal">Inform Primitives</a> and <a href="M-ia.html" class="internal">Inform Annotations</a>.
</p>

<p class="commentary">Similarly, the Inter specification allows great flexibility in how packages are
used to structure a program, but the Inform toolchain has definite ideas about
that &mdash; as follows.
</p>

<p class="commentary firstcommentary"><a id="SP2" class="paragraph-anchor"></a><b>&#167;2. Global area and main.</b>As in every Inter program, the global area (outside of all packages) simply
defines packages and pragmas. At present, Inform generates pragmas only for
Inform 6 memory settings: even those are now probably not needed, and may go.
All of the actual program is in the <span class="extract"><span class="extract-syntax">/main</span></span> package, which has type <span class="extract"><span class="extract-syntax">_plain</span></span>.
</p>

<p class="commentary"><span class="extract"><span class="extract-syntax">/main</span></span> contains the standard subpackages <span class="extract"><span class="extract-syntax">/main/architecture</span></span> and <span class="extract"><span class="extract-syntax">/main/connectors</span></span>,
both of which have type <span class="extract"><span class="extract-syntax">_linkage</span></span>. The first defines architectural constants
such as <span class="extract"><span class="extract-syntax">WORDSIZE</span></span>, while the second is used to manage the import and export of
symbols while linking trees together, and cannot contain content other than
symbols. Neither really contains the program as such.
</p>

<p class="commentary firstcommentary"><a id="SP3" class="paragraph-anchor"></a><b>&#167;3. Compilation modules.</b>The only other content of <span class="extract"><span class="extract-syntax">/main</span></span> is its set of "modules". Each one is a subpackage
of type <span class="extract"><span class="extract-syntax">_module</span></span>. They originate as follows:
</p>

<ul class="items"><li>(a) The "generic module" <span class="extract"><span class="extract-syntax">/main/generic</span></span> contains material which is the same
on every run. For example, the definition of the typename <span class="extract"><span class="extract-syntax">text_literal</span></span> can
be found here.
</li><li>(b) There is one module for each "compilation unit" of source code contributing
to the program. <span class="extract"><span class="extract-syntax">/main/source_text</span></span> is always one of these, and contains matter
coming directly from the main I7 source text. There is then one compilation
unit for each included extension, such as <span class="extract"><span class="extract-syntax">/main/locksmith_by_emily_short</span></span>,
and one for each included kit of Inter code, such as <span class="extract"><span class="extract-syntax">/main/BasicInformKit</span></span>.
</li><li>(c) <a href="../inform7/index.html" class="internal">inform7</a> also produces the "completion module" <span class="extract"><span class="extract-syntax">/main/completion</span></span>,
which contains resources put together from the (natural language part of) the
program as a whole, but which can't be tied to any specific compilation unit.
For example, in an interactive fiction project, the spatial map is such a
resource.
</li><li>(d) <a href="index.html" class="internal">inter</a> also produces the "synoptic module" <span class="extract"><span class="extract-syntax">/main/synoptic</span></span>, which
contains material indexing and cross-referencing material in the other modules.
This is built last of all. For example, the synoptic module includes an array
at <span class="extract"><span class="extract-syntax">/main/synoptic/actions/ActionCoding</span></span> which consolidates metadata on all
of the actions present in the program. This could not have been made as
part of the completion module because it includes references to actions only
found in the kits, and could not have been made as part of any kit because
it includes references to actions found only in the I7 source text.
</li></ul>
<p class="commentary">In a sense the completion and synoptic modules play a similar role to each
other, and a long-term aspiration might be to move more of the former into
the latter, with a view to full linking of code some day. (At present the
tool-chain can precompile &mdash; "assimilate" &mdash; kits and link them in, but not
extensions written in Inform 7 source text.) Many structural choices have
been made in order to keep this option open, but it is not simple to do.
</p>

<p class="commentary firstcommentary"><a id="SP4" class="paragraph-anchor"></a><b>&#167;4. </b>Thus the modules are not all produced at the same time, and several are
produced independently. The module for each kit, in particular, is essentially
compiled as a stand-alone Inter program and only joins the finished program
at the linking stage.
</p>

<pre class="displayed-code all-displayed-code code-font">
<span class="plain-syntax">+-------------------------------+   +---------------------+   +---------------------+</span>
<span class="plain-syntax">|   </span><span class="element-syntax">architecture</span><span class="plain-syntax">                |   |   </span><span class="element-syntax">architecture</span><span class="plain-syntax">      |   |   </span><span class="element-syntax">architecture</span><span class="plain-syntax">      |</span>
<span class="plain-syntax">|   </span><span class="element-syntax">generic</span><span class="plain-syntax">                     |   |   </span><span class="element-syntax">BasicInformKit</span><span class="plain-syntax">    |   |   </span><span class="element-syntax">WorldModelKit</span><span class="plain-syntax">     |</span>
<span class="plain-syntax">|   </span><span class="element-syntax">source_text</span><span class="plain-syntax">                 |   |   </span><span class="element-syntax">connectors</span><span class="plain-syntax">        |   |   </span><span class="element-syntax">connectors</span><span class="plain-syntax">        |</span>
<span class="plain-syntax">|   </span><span class="element-syntax">locksmith_by_emily_short</span><span class="plain-syntax">    |   +----------+----------+   +----------+----------+</span>
<span class="plain-syntax">|   ...                         |      </span><span class="function-syntax">INTER</span><span class="plain-syntax">   |                 </span><span class="function-syntax">INTER</span><span class="plain-syntax">   |</span>
<span class="plain-syntax">|   </span><span class="element-syntax">completion</span><span class="plain-syntax">                  |              |                         |</span>
<span class="plain-syntax">|   </span><span class="element-syntax">connectors</span><span class="plain-syntax">                  |              |                         |   ...</span>
<span class="plain-syntax">+------------------+------------+              |                         |</span>
<span class="plain-syntax">    </span><span class="function-syntax">INFORM7</span><span class="plain-syntax">         \                          |                         |</span>
<span class="plain-syntax">                     \                        \|/                       \|/</span>
<span class="plain-syntax">                      \-----------------------&gt;</span><span class="element-syntax">o</span><span class="plain-syntax">-----------&gt;</span><span class="element-syntax">o</span><span class="plain-syntax">&lt;-----------</span><span class="element-syntax">o</span><span class="plain-syntax">---- ...</span>
<span class="plain-syntax">                                                            |</span>
<span class="plain-syntax">                                                            | </span><span class="function-syntax">INTER</span>
<span class="plain-syntax">                                                            |</span>
<span class="plain-syntax">                                                           \|/</span>
<span class="plain-syntax">                                            +---------------+---------------+</span>
<span class="plain-syntax">                                            |   </span><span class="element-syntax">architecture</span><span class="plain-syntax">                |</span>
<span class="plain-syntax">                                            |   </span><span class="element-syntax">generic</span><span class="plain-syntax">                     |</span>
<span class="plain-syntax">                                            |   </span><span class="element-syntax">source_text</span><span class="plain-syntax">                 |</span>
<span class="plain-syntax">                                            |   </span><span class="element-syntax">locksmith_by_emily_short</span><span class="plain-syntax">    |</span>
<span class="plain-syntax">                                            |   ...                         |</span>
<span class="plain-syntax">                                            |   </span><span class="element-syntax">completion</span><span class="plain-syntax">                  |</span>
<span class="plain-syntax">                                            |   </span><span class="element-syntax">BasicInformKit</span><span class="plain-syntax">              |</span>
<span class="plain-syntax">                                            |   </span><span class="element-syntax">WorldModelKit</span><span class="plain-syntax">               |</span>
<span class="plain-syntax">                                            |   ...                         |</span>
<span class="plain-syntax">                                            |   </span><span class="element-syntax">synoptic</span><span class="plain-syntax">                    |</span>
<span class="plain-syntax">                                            |   </span><span class="element-syntax">connectors</span><span class="plain-syntax">                  |</span>
<span class="plain-syntax">                                            +-------------------------------+</span>
</pre>
<p class="commentary firstcommentary"><a id="SP5" class="paragraph-anchor"></a><b>&#167;5. </b>Modules subdivide the program by origin. But each module is further subdivided
into "submodules", packages of type <span class="extract"><span class="extract-syntax">_submodule</span></span>, and those divide it by its
ingredients. For example, the global variables in module <span class="extract"><span class="extract-syntax">M</span></span> will all be in
the submodule <span class="extract"><span class="extract-syntax">/main/M/variables</span></span>.
</p>

<p class="commentary">At present, the full range of possible subpackages is:
</p>

<pre class="displayed-code all-displayed-code code-font">
<span class="plain-syntax">    /main/M/actions</span>
<span class="plain-syntax">    /main/M/activities</span>
<span class="plain-syntax">    /main/M/adjectives</span>
<span class="plain-syntax">    /main/M/arrays</span>
<span class="plain-syntax">    /main/M/basics</span>
<span class="plain-syntax">    /main/M/bibliographic</span>
<span class="plain-syntax">    /main/M/chronology</span>
<span class="plain-syntax">    /main/M/commands</span>
<span class="plain-syntax">    /main/M/conjugations</span>
<span class="plain-syntax">    /main/M/constants</span>
<span class="plain-syntax">    /main/M/extensions</span>
<span class="plain-syntax">    /main/M/functions</span>
<span class="plain-syntax">    /main/M/grammar</span>
<span class="plain-syntax">    /main/M/instances</span>
<span class="plain-syntax">    /main/M/interactive_fiction</span>
<span class="plain-syntax">    /main/M/kinds</span>
<span class="plain-syntax">    /main/M/multimedia</span>
<span class="plain-syntax">    /main/M/phrases</span>
<span class="plain-syntax">    /main/M/properties</span>
<span class="plain-syntax">    /main/M/relations</span>
<span class="plain-syntax">    /main/M/responses</span>
<span class="plain-syntax">    /main/M/rulebooks</span>
<span class="plain-syntax">    /main/M/rules</span>
<span class="plain-syntax">    /main/M/scenes</span>
<span class="plain-syntax">    /main/M/table_columns</span>
<span class="plain-syntax">    /main/M/tables</span>
<span class="plain-syntax">    /main/M/tests</span>
<span class="plain-syntax">    /main/M/</span><span class="reserved-syntax">text</span>
<span class="plain-syntax">    /main/M/use_options</span>
<span class="plain-syntax">    /main/M/variables</span>
</pre>
<p class="commentary firstcommentary"><a id="SP6" class="paragraph-anchor"></a><b>&#167;6. </b>Metadata is extensively used throughout Inter trees generated by Inform.
This is not simply to serve human readers who happen to be glancing at them:
it's essential to the process that generous and systematic metadata is present,
because both the synoptic module and the index<sup id="fnref:1"><a href="#fn:1" rel="footnote">1</a></sup> for a project are both generated
using that metadata.
</p>

<ul class="footnotetexts"><li class="footnote" id="fn:1"><p class="inwebfootnote"><sup id="fnref:1"><a href="#fn:1" rel="footnote">1</a></sup> Again, this architectural choice is more work for us &mdash; it was much easier
to produce the index higher up in the compiler, as was done until 2021 &mdash; but
generating the index only in <a href="index.html" class="internal">inter</a> right at the end of the compilation
process, using only the Inter tree and its metadata, leaves open the possibility
of fuller linking of Inter code later on.
<a href="#fnref:1" title="return to text"> &#x21A9;</a></p></li></ul>
<p class="commentary firstcommentary"><a id="SP7" class="paragraph-anchor"></a><b>&#167;7. </b>As an example, every module includes metadata at its top level like so:
</p>

<pre class="displayed-code all-displayed-code code-font">
<span class="plain-syntax">    </span><span class="reserved-syntax">package</span><span class="plain-syntax"> main _plain</span>
<span class="plain-syntax">        ...</span>
<span class="plain-syntax">        </span><span class="reserved-syntax">package</span><span class="plain-syntax"> basic_inform_by_graham_nelson _module</span>
<span class="plain-syntax">            </span><span class="reserved-syntax">constant</span><span class="plain-syntax"> (</span><span class="reserved-syntax">int32</span><span class="plain-syntax">) ^category = </span><span class="constant-syntax">3</span>
<span class="plain-syntax">            </span><span class="reserved-syntax">constant</span><span class="plain-syntax"> (</span><span class="reserved-syntax">text</span><span class="plain-syntax">) ^author = </span><span class="string-syntax">"Graham Nelson"</span>
<span class="plain-syntax">            </span><span class="reserved-syntax">constant</span><span class="plain-syntax"> (</span><span class="reserved-syntax">text</span><span class="plain-syntax">) ^title = </span><span class="string-syntax">"Basic Inform"</span>
<span class="plain-syntax">            </span><span class="reserved-syntax">constant</span><span class="plain-syntax"> (</span><span class="reserved-syntax">text</span><span class="plain-syntax">) ^</span><span class="reserved-syntax">version</span><span class="plain-syntax"> = </span><span class="string-syntax">"1"</span>
<span class="plain-syntax">            </span><span class="reserved-syntax">constant</span><span class="plain-syntax"> (</span><span class="reserved-syntax">text</span><span class="plain-syntax">) ^credit = </span><span class="string-syntax">"Basic Inform version 1 by Graham Nelson"</span>
<span class="plain-syntax">            </span><span class="reserved-syntax">constant</span><span class="plain-syntax"> (</span><span class="reserved-syntax">int32</span><span class="plain-syntax">) ^modesty = </span><span class="constant-syntax">0</span>
<span class="plain-syntax">            </span><span class="reserved-syntax">constant</span><span class="plain-syntax"> (</span><span class="reserved-syntax">int32</span><span class="plain-syntax">) ^word_count = </span><span class="constant-syntax">7691</span>
<span class="plain-syntax">            ...</span>
</pre>
<p class="commentary firstcommentary"><a id="SP8" class="paragraph-anchor"></a><b>&#167;8. Function packages.</b>All functions are expressed in Inter code by packages of type <span class="extract"><span class="extract-syntax">_function</span></span>.
This contains the function body as a subpackage, but it may also contain
resources needed by that function body &mdash; for example, literal texts, arrays
and so on. (The idea is that a <span class="extract"><span class="extract-syntax">_function</span></span> package can be "transmigrated"
from one tree to another, without losing the resources it depends on.)
</p>

<p class="commentary">Usually this <span class="extract"><span class="extract-syntax">_function</span></span> package will contain only one function body, often
but not always called just <span class="extract"><span class="extract-syntax">call</span></span>:
</p>

<pre class="displayed-code all-displayed-code code-font">
<span class="plain-syntax">                </span><span class="reserved-syntax">package</span><span class="plain-syntax"> rule_fn _function</span>
<span class="plain-syntax">                    </span><span class="reserved-syntax">package</span><span class="plain-syntax"> call _code</span>
<span class="plain-syntax">                        ...</span>
</pre>
<p class="commentary">But if the function needs to manipulate or refer to data not expressible in
single words, such as lists or texts, then it will probably need to create and
subsequently destroy a stack frame. The mechanism will then be:
</p>

<pre class="displayed-code all-displayed-code code-font">
<span class="plain-syntax">                </span><span class="reserved-syntax">package</span><span class="plain-syntax"> rule_fn _function</span>
<span class="plain-syntax">                    </span><span class="reserved-syntax">package</span><span class="plain-syntax"> call _code</span>
<span class="plain-syntax">                        ...</span>
<span class="plain-syntax">                    </span><span class="reserved-syntax">package</span><span class="plain-syntax"> kernel _code</span>
<span class="plain-syntax">                        ...</span>
</pre>
<p class="commentary">The "shell" function, <span class="extract"><span class="extract-syntax">call</span></span>, creates a stack frame and then calls the "kernel"
function, which does the actual work; when that returns to the "shell", the
stack frame is disposed of again. This is all transparent to the user, who
simply calls <span class="extract"><span class="extract-syntax">call</span></span> and doesn't need to know which mechanism is in play.
</p>

<p class="commentary firstcommentary"><a id="SP9" class="paragraph-anchor"></a><b>&#167;9. Looking at the Inter produced.</b>The following commands produce the final state of the Inter code for the test
case <span class="extract"><span class="extract-syntax">Acidity</span></span>, in binary and textual form:
</p>

<pre class="ConsoleText-displayed-code all-displayed-code code-font">
<span class="ConsoleText-element-syntax">$</span><span class="ConsoleText-plain-syntax"> </span><span class="ConsoleText-function-syntax">'inform7/Tangled/inform7'</span><span class="ConsoleText-identifier-syntax"> -source</span><span class="ConsoleText-plain-syntax"> inform7/Tests/Test\ Cases/Acidity.txt</span><span class="ConsoleText-identifier-syntax"> -o</span><span class="ConsoleText-plain-syntax"> Acidity.interb</span><span class="ConsoleText-identifier-syntax"> -format</span><span class="ConsoleText-plain-syntax">=binary</span>
<span class="ConsoleText-element-syntax">$</span><span class="ConsoleText-plain-syntax"> </span><span class="ConsoleText-function-syntax">'inform7/Tangled/inform7'</span><span class="ConsoleText-identifier-syntax"> -source</span><span class="ConsoleText-plain-syntax"> inform7/Tests/Test\ Cases/Acidity.txt</span><span class="ConsoleText-identifier-syntax"> -o</span><span class="ConsoleText-plain-syntax"> Acidity.intert</span><span class="ConsoleText-identifier-syntax"> -format</span><span class="ConsoleText-plain-syntax">=text</span>
</pre>
<p class="commentary">Be warned that these are large: they have several large kits linked into them
by the time they have reached this final state, and thus contain many modules.
<span class="extract"><span class="ConsoleText-extract-syntax">Acidity.intert</span></span> runs to about 250,000 lines of textual Inter.
</p>

<p class="commentary">It's also possible to access the Inter output by the top half of <a href="../inform7/index.html" class="internal">inform7</a>
before it passes through any linking process: simply add <span class="extract"><span class="ConsoleText-extract-syntax">-pipeline unlinked</span></span>.
Unlike the default pipeline <span class="extract"><span class="ConsoleText-extract-syntax">-pipeline compile</span></span>, <span class="extract"><span class="ConsoleText-extract-syntax">unlinked</span></span> just saves out
the Inter straight to an external file. (Of course, saving out unlinked Inter
to a format like Inform 6 will not produce viable code: linking is done for
a reason.)
</p>

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